The invention relates to a method of providing a paste on a substrate surface by dipping.
The invention relates in particular to a method of manufacturing a ceramic multilayer actuator and to a ceramic multilayer actuator having end contacts which are manufactured by the method according to the invention.
Pastes are used, for example, for applying resistive layers or electrode layers to electric components such as resistors, capacitors and supports of semiconductor devices. According to methods which are known per se, such pastes cannot only be provided by dipping but also by screen printing.
Under the influence of an applied electric field, the dimensions of piezoelectric elements, such as actuators, may change and said piezoelectric elements may exert a mechanical force. In certain embodiments, end contacts are used to interconnect inner electrodes and to provide the connection with an external power source. Actuators are used, inter alia, in accurate positioning devices and in printers.
In U.S. Pat. No. 4,859,498 a description is given of a device for and a method of providing a silver-containing conductive paste on electronic components. The paste is applied in the form of a thin layer to a flat plate, after which the electronic components are dipped in the paste. Subsequently, the end contacts thus formed are baked. According to an alternative embodiment, the paste is contained in a porous member such as, for example, a sponge.
According to the known method, end contacts are formed about the end portions of the electronic component in such a manner that also a part of the side faces of the component is covered. This is desirable for many applications, for example, for components which are to be soldered on a printed circuit board. For other applications, however, such as for ceramic actuators which can be stacked and interconnected to attain a cumulative mechanical effect, it may be necessary to leave the side faces of the component uncovered. Another disadvantage of the known method is that, in general, the surface of the end contact formed is not completely flat, which can be ascribed to the manner in which the paste loosens itself from the surface when the component is removed from the paste after the dipping operation.